Intervention with mixed probiotics (Bifidobacterium longum, Lactobacillus acidophilus, and Enterococcus faecalis) has been shown to significantly relieve IBS symptom severity scale (IBS-SSS) scores in patients with IBS and diarrhea (IBS-D), relieve abdominal pain symptoms, and reduce plasma monocyte chemoattractant protein-1 (MCP-1) and IL-1β levels (Zhang et al., 2019a). The gene discussed is CCL2; the disease is irritable bowel syndrome.